Esters of aroyl benzoic acids



Patented Mar. 4, 1941 PATENT OFFICE ESTERS 0F AROYL BENZOIC ACIDS Herman A. Bruson, Philadelphia, Pa., assignor, by

mesne assignments,

to American Gyanamid Company, New York, N. Y.

No Drawing. Appli cation October 3, 1929,

Serial No. 397,143

8 Claims.

This invention relates to organic solvents and more particularly to aliphatic or aromatic esters of monobasic keto-benzoic acids having the general formula RCORCOOH wherein R and R represent aromatic nuclei.

Typical acids which belong to this class are:

Ortho-benzoyl-benzoic acid 0 O O H Para-toluoyl-o-benzoic acid OOOH Naphthoyl-o-benzoic acid and their derivatives such as 2,4-dich1orobenzoylo-benzoic acid, methyl-isoprop-yl-benzoyl-o-benzoic acid (cymoyl-o benzoic acid), and the like.

The lower esters of some of these acids, such as the methyland ethylesters, have in part already been described in the literature as crystalline solids. They have not however found any extensive commercial application in the arts.

Moreover, it could not have been foretold that the higher esters of these acids would form valuable, high boiling oily liquids which solubilize nitrocellulose and which can be used in conjunction with other solvents in the preparation of pyroxylin lacquers, as plasticizers for the final I nitro-cellulose film.

We have discovered that the higher esters of the aforementioned keto-benzoic acids possess physical properties which are desirable in plasticizers for nitrocellulose or acetyl cellulose films.

They are all high boiling, heavy liquids having a marked solubilizing action upon nitrocellulose and possessing sufi'icient tackiness to give the film in which they are present a certain degree of adhesion.

The esters which we have prepared are all derived from saturated monohydric alcohols which contain three or more carbon atoms in the molecule, such as iso-propyl, butyl, iso'amyl, betaethoxyethyl, beta-butoxyethyl, benzyl and cyclohexyl alcohols. These esters may all be prepared by heating the corresponding monohydric alcohol with any one of the keto-benzoic acids having the general formula,

wherein R and R, are aromatic nuclei, in the presence of a dehydration catalystsuch as su1- phuric acid, hydrochloric acid, zinc chloride, or the like; subsequently removing the catalyst, distilling off the excess of alcohol, and fractionating the residual oil in vacuo.

Illustrations are given below of the general method of preparation of the above esters, as well as a table of the physical properties of other typical esters of the same class, which we have prepared as new compounds.

EXAMPLE 1 Butyl-o-benzoyl benzowte A mixture of gramsortho-benzoyl-benzoic acid, 150 cubic centimeters butyl alcohol, and a dehydration catalyst, preferably 10 cc. of concentrated sulphuric acid (Sp. Gr. 1.84) are refluxed at the boiling point for eight hours. The mixture is allowed to cool and is then washed, first with water to remove the sulphuric acid, then with dilute sodium carbonate solution, and finally with water to remove traces of alkali. The oil is then fractionated. At first unchanged butyl alcohol distills over. The butyl ester then comes over as a colorless, limpid, oily liquid, boiling at 241-244" C. under 20 m. m. pressure.

EXAMPLE 2 Cycloheazyl ester of para-toluoyZ-o-benzoic acid Boil under reflux, a mixture of '75 gr. paratoluoyl-o-benzoic acid, 150 cc. cyclohexanol, and 10 cc. concentrated sulphuric acid for 6 hrs. After cooling, the product is washed with water and sodium carbonate solution until all traces of free acid are removed. The excess cyclohexanol is then distilled ofi at reduced pressure; The residual high boiling oil is fractionated in vacuo, whereupon the cyclohexyl ester distills over at 252254 C. under '7 m. m. pressure. It forms a thick, colorless viscous oil.

EXAMPLE 3 Beta-ethory-ethyl ester of ortho-bc'neoyl beneoic acid To cubic centimenters of ethylene glycolmono-ethyl ether, C2I-I5--OCH2CH2OH, 50 gr. of ortho-benzoyl benzoic acid and 10 cc. concentrated sulphuric acid are added, and the mixture is boiled for 3 hours under reflux. The cooled liquid is washed with Water and dilute sodium carbonate solution to remove excess alcohol and eral class, may be used. Thus We have successfully employed para-ethyl-benzoyl-o-loenzoic acid, dimethyl-benzoyl-o-benzoic acid, para-phenylbenzoyl-o-benzoic acid, alphaand beta-methyl acid, and the residual ester fractionated in Vacuo. naphthoyl-o-benzoic acids, a-chlornaphthoyl-o- It comes over as a colorless oil at 221-225 C. unbenzoic acid and tetrahydro-naphthoy1-o-benzoic der 5 m. m. pressure. acid for preparing similar esters. It is to be EXAMPLE 4 understood that the above examples are merely illustrative and that the invention is not conuiy -OTfiO-flaphthogl beneoate fined to any specific. temperatures, methods of 50 grams f orthomwhthwhbenzoic acid are operation, materialsused, etc., since the scope of boiled under reflux with 100 cc. of butyl alcohol mventlon is hmltej only as mdlcated m the and 10 cc. concentrated sulphuric acid for 5 hours. clalms The cooled liquid is washed'free from unchanged h m 155 acid and catalyst with water and sodium carbon- AS new compound an ester of the general} ate solution, and the residualoil is fractionally P -B"- "Q Where R and R distilled in vacuo. At first unchanged butyl alcoare mom-aim 11116161 and X 1s W hol came over. The ester then distilled over as a AS a w compound, e y y ester o slightly yellowish, very viscous oil, boiling at- D u y -be 01c aCld.

0 258-263 C. under 5 m. m. pressure. I 3. The step in the process of preparing the In a similar way, using the same relative quanbutyl ester of para-toluoyl-ortho-benzoic acid tities of keto-acid, alcohol, and sulphuric acid, which consists in condensing said acid with excess and boiling for 6 to 8 hours under reflux, the folbutyl alcohol in the presence of sulphuric acid. lowing esters were prepared. 4. As a new compound an ester of the general Acid used Ester Boiling point of ester Properties Ortho-benzoyl-benzoic lso-propyl 240-243" O./20n1m Heavy colorless ll Iso-amyl 2l52l8 0J4 mm Col rliess, oily Ii- 11 Benzyl 278282 O./l6 mm q 1 30. Cyolohexyl 251254 C./l0 11min." Do. Beta-butoxy-ethyl 224-229 0J4 mm Do. Capryl 264268 C./2O mm Do. Isopropyl 217-218 C./8 mm Do. N -but 244248 O./l7 mm Do. Is0-amyl.. 224228 0.]4 mm Do. Beta-ethoxy-etliyl 237-238 O./5 mm Do.

Do Benz 3053l0 C./4mm Do. 2-4-dichloro-benzoyl-benzoic n-Butyl 232-237" C./7 mm Do. Ortho-naphthoyl-benzoic Benzyl 3l53l8 O./5 mm Heavy oil.

Do Cyclohexyl Above 320 014 mm Very viscous oil.

All of the above esters may be used as plasticizers for nitrocellulose or for acetyl cellulose. Other esters of acids belonging to the general class I wherein R and R are aromatic nuclei, may likewise be prepared for the same purpose. These include the propyl, iso-butyl, amyl, bornyl and methylcyclohexyl esters. All of these estersmay be represented by the following general formula:

R-co R" coox forinula R--CO-R'-CO-OX where R and R are aromatic nuclei, and X is a cyclohexyl group.

5. As a new compound an ester of the general formula Pv-CORCO-OX.whe-re R, and R are aromatic nuclei and X is a saturated aliphatic organic radical having from 3 to 10 carbon atoms.

6. An ester of benzoylbenzoic acid and a satu rated monohydric paraffin alcohol, containing more than two and less than eight carbon atoms.

7. An ester of a diarylketoneorthocarbo-xylic acid of the formula RCORCOOH, and a saturated monohydric alcohol of the paraffin series having more than two carbon atoms, R and R being aromatic nuclei free from halogen and hydroxyl substituents;

8. An ester of ben zoylbenzoic acid with a saturatedrnonohydric parafiin alcohol of a molecular Weight greater than 46.

HERMAN A. BRUSO-N. 

